Hi Peter, On Wed, Dec 16, 2015 at 2:11 AM, Peter Chen <peter.chen@xxxxxxxxxxxxx> wrote: > Thanks, Fabio, but I am curious how things like that? The USBOH3 clock > is not opened, the usb driver will hang when it tries to access > registers. If this clock is always on, then, why the system will > hang later? I found the issue with your patch. You missed to add the pinctrl node. With the change below USB is functional in Udoo: --- a/arch/arm/boot/dts/imx6qdl-udoo.dtsi +++ b/arch/arm/boot/dts/imx6qdl-udoo.dtsi @@ -22,6 +22,8 @@ usb_hub1 { compatible = "generic-onboard-hub"; + pinctrl-names = "default"; + pinctrl-0 = <&pinctrl_usbh>; clocks = <&clks IMX6QDL_CLK_CKO>; reset-gpios = <&gpio7 12 GPIO_ACTIVE_LOW>; reset-duration-us = <2>; -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html